Pigments can be dispersed or suspended in a liquid vehicle to be utilized in inks. A variety of pigments can be difficult to disperse and stabilize in water-based vehicles due to the nature of the surface of pigments and the self-assembling behavior of pigments. One way to facilitate color pigment dispersion and sustained suspension in a liquid vehicle is to adding a dispersant, such as a polymer, to the liquid vehicle. Another way to stabilize pigment is to covalently attach a small molecule, oligomer, or polymer to a surface of the pigment to form a self-dispersed pigment. Regardless of the technique of dispersion, the attached or unattached dispersant can stabilize the pigment in the liquid. Pigments that are otherwise stable in liquid vehicles can often penetrate print media, resulting in low color saturation or black optical density. Thus, enhancing color saturation or black optical density of ink compositions containing pigments would be a desirable property to achieve generally.